Method for transmitting alpha plurality of communications



April 5, 1932. w. P. c. VAN DER HORST METHOD FOR TRANSMITTING A PLURALITY OF COMMUNICATIONS F'i-led Dec. 4, 1930 2 Sheets-Sheet l FIII: Iii filial Eg 16f- W My //urst April 5, 1932.- w. P. c. VAN'DER HORST 1,352,727

METHOD FOR TRANSMITTING A PLURALITY OF COMMUNICATIONS Filed Dec. 4, 1930 2 Sheets-Sheet 2 an fi/ars aim 55m Patented Apr. 5, 1932 UNITED STATES PATENT OFFICE WILLEM PIETER CORNELIS VAN DER HORST, OF THE HAGUE, NETHERLANDS METHOD FOR TRANSMITTING A PLURALITY F EOMMUNICATION S Application filed December 4, 1930, Serial! 500,149, and in the Netherlands December 4, 1929.

The presentinvention relates to the simultaneous transmission or broadcasting of a plurality of communications, each of which is separately recorded either mechanically, for

6 example on a wax cylinder; magnetically, for example on a magnetized wire or band; or in any other well-known manner, e. g. optically.

According to thisinvention use is made of According to the invention in the transmis.

- sion of prevlously recorded messages or communications, the gaps 1n .one message are filled up with parts of other messages without the necessity of widening. A certain. secrecy as well as a saving in time is thus:

obtained;

During the transmission of a communication recorded for example on a band, a second band is put into operation as soon as the oscillations or oscillatory currents due-to the first band cease. transfers its communication to the transmit- 'ter until such time as the first band, which continues in operation, again causes the production of oscillatory currents, at which time the second hand is stopped automatically. In carrying out the invention a branch cir- 40 cult is arranged in the transmitted circuit which branch circuit influences a contact in such manner that it remains open asjlong as the oscillations are maintained. When these cease, this contact closes a circuit which causes a second band to start. When the oscillations due to said'second band are no longer pro duced, a third band is set into motion unless in themeantime the first band has again ben to transmit oscillations, in which case the ist The second band'in' turn band alone is operative. Each time a new circuit is made, a signal or impulse is transmitted which influences contacts on the receiver.

The transmitter and receiver may be so constructed that in case oscillations are not transmitted from any of the three bands, a fourth band is put into operation, etc.

According to a modification of the system comprising the invention, each band in turn is arranged to become the continuously moving band, so that the several, communications are more equally transmitted. The contacts are arranged in such manner that band II becomes band I, band III becomes band II, and band IV becomes band III after a certain number of pauses in the oscillations received fromthe continuously moving band. Itwill d be understood that when this modification is not made, a subsequent" band, for example the fourth, usually remains idle for toolong. periods as the earlier bands transmit practically continuous oscillations.

The device may be adjusted in such manner that the switch-over is effected only by pauses of a duration longer than a predetermined time, shorter pauses being inefi'ective.

By way of illustration certain details of a possible arrangement, will be discussed, solely for explanatory purposes, in connection with the accompanying drawings.

Fig. 1 is a schematic view, showing a number of bands, p

Fig. 2 is a fragmentary schematic view illustrating how the bands are brought into v action,

Fig. 3 is a general schematic view, illustrating the details for the application of the principle demonstrated by Fig. 2, r

Fig. 4, a further schematic view, shows how the bands are put into operation and how they are stopped. (This mechanical device is disclosed merely to facilitate explanations; the use of a thermionic device, havin practi'cally no moments of inertia is possible and therefore recommended.)

Fig. 5 shows an extended application of a detail in Fig. 3. Fig; 1 showsanumber of circuits,each comprising a microphone 1, of such construction (not shown), that oscillations caused by breathing or such like are not recorded, so that the pauses become great magnet 5 which reproduces the oscillatory 1 current in the output line. The movement of the band is controlled by the device 7.

As long as the first band oscillates, the device 7, which. will be further described here- ,inafter, prevents the further bands from moving. As soon as no further oscillatory current is received from the first band the device 7 effects a connection by which the following band is put into operation, and so on.

Fig. 2 shows how in the magnet 5 an oscillatory current is induced which is sent to the transmitter through the line 8. A branch current at 7 controls the movement mecha- .nism 9 of the next band.

Fig. 3 shows a more sensitive device wherein the oscillatory current induced in the device 5 influences at 7 the system of a sensitive alternating current mirror -galvanometer. The light of a lamp 1O falls upon a photoelectric cell 11, by which a current circuit of the mechanism of movement over combination 12 is closed. The band 4a starts and the galvanometer 7a deflects, as a result of which light falls upon the cell 13a. If in the meantime a pause occurs in the band 4a, and assuming that in band 4 the pause still continues, the mirror of 7 a returns into its position of rest, throws light upon cell 11a and starts a third band. In the meantime the pause in band 4 has ended, the mirror 7 is brought out of its position of rest and the circuit 12 is interrupted. In order to prevent the mirrors of the following galvanometers 70, etc. from returning into their position of rest due to the above mentioned ending of the pause and thus starting up the bands 4a, etc, the cells 13, 13a, etc. have been provided. Their circuits influence corresponding extra windings which prevent the non-moving bands from switching on the cells 11a, etc.

Summarizing the following takes places The band 4 transmits oscillations; the ray of light is. directed towards 13, 13a, etc., the circu1ts1112, 11a12c'z, etc. are currentless. The band 4 now reaches a pause. The ray of light is directed towards 11, while circuit 13 is currentless. Circuit 11-12 is live and conse uently band 4a moves. If then band 4a emits, the ray of light remains directed towards 13a. Consequently the third galvanometer is kept alive and Ila-42a, etc. remain currentless.

Finally there are meters 6 in the main current circuits, which may be so adjusted, that if desired, the preceding band unit may put out of action after any desired number of pauses.

If in practice, pauses of a certain minimum adjusted in such manner that only after a certain lapse of time will they permit current to pass, or else cells possessing these propertiesshould be used for such purpose. 1

Fig. 4 shows the device for stopping and puttingbin, motion the band 4. The latter is moved y a disc 14 having soft iron discs attached on both sides. On the one side a magnetic system 15 rotates at the rate corresponding to the speed of the bands. On the other side there 1s'a stationary magnetic system 16. A. local current can" now be so connected that if cell 11 permits current to pass due to the deflection of the galvanometer 71(Fig. 3) it' either influences the rotating magnetic system or the stationarymagnetic system.

To stop the band the circuit of the rotating magnetic system 15 is broken and the circuit of thest-ationary system 16 is closed. Consequently the disc is immediately caught and stopped.

To counteract the effect of the inertia of the disc, when the band starts or stops, the pickup iscauscd to move in a direction opposite to the direction of the applied forces at a speed varying directly in accordance with the speed of acceleration or retardation of the band.

Fig. 5 showsan improvement by which another band is switched on only when a pause in the previous band is of sufficient duration.

Should pauses of a very short. duration cause unsatisfactory working of the entire set because of the inertia of the working parts,

suitable adjustable cells or relays can be applace the adjustable cells or relays 11.

To demonstrate the principle, a second pick-up is used as a recording element. If we assume that pauses of a shorter duration than e. g. 1 second are not to be used, the pick-up 5 is placed before the pick-up 5?) at a distance corresponding to the displacement of the band in a one-second interval.

An extra current is applied to cell 7 (which to facilitate explanationha's been shown as a mirror galvanometer) said circuit being controlled by the pick-up 5 connected to a light relay 17, which should likewise be adjusted to give a retardation of one second.

So long'as the band cmitsoscillations, the two circuits support each other. If the pickup 5 encounters a pause-gap, it records no more oscillations and the relay 17 breaks this circuit,but in this instance only after one second has elapsed. In this interval the.

pause-gap has covered; the distance between pick-up 5 and pick-up 5b. The circuit of the pick-up 56 now also transmits no oscillations, so that the cell 11 is switched on. This occurs when the pause-gap is greater than one second.

: pied in the eeann"! Ifthereafter an oscillatory section of the band arrives at the pick-u 5, the circuit 18 is again switched on, but t e current in this circuit alone is not able to deflect the galvanometer (inertia of cell 17) so that thedeflection finally only occurs when the oscillatory section has arrived at pick-up 5?).

If a pause-gap shorter than one "second passes the pick-up 5, there will be no time left for'the light relay 17 to interrupt the current in circuit 18 and therefore the galvanometer-mirror remains in its position because an oscillatory current is impressed at 5 withinthe time of one second.

Thus it will be understood that when a shorter pause-gap than one second passes under pick-up 5b, the circuit of the latter only is made currentless, but since circuit 18 does not support the current flow, 11 cannot be switched on, so that this shorter pause is not used.

Finally the following may be observed with regard to the manner in which the mixture of speechesis divided into its component parts at the receiving side. For the receiving side the operation of the transmitter may be reversed. Thenit is only the question how.

the received signs should be distributed upon the bands in question.

Besides the possib mitted the impulses of the mechanism of movement by modulators of difl'erent frequency and separating them in the receiver b means of filters, the following may be approject as drawn. It will be noted that ce ls 11 etc. are arranged in the circuit to the transmitter. If the ray of light falls upon 11 etc. acurrent impulse will be produced in the transmitter, the strength of this impulse being proportioned to that of the source of light. By varying the strengths of the different sources of light apparatus will also In case the cells in uestion inthe receivingapparatus have een turned to those various impulses of light and connected with,

the current circuit of the mechanism of movement of the corr spending band, it will be clear that the lig t impulse from e. .-cell 11, which puts into operation band 4a m the transmitter, also starts band 4a in the receiving, apparatus. If-for example for this purpose Kerr-cells are used in the receiving apparatus, said cells may be adjusted or constructed in such manner that only at a predetermined voltage is the polarization' plane'altered and the cell lets light pass, i

whichis thrown upon the corresponding Q- light relay, which then closesthe circuit ofthecorresponding band. V It is essential of course that with the re oeiving apparatus similar-precautions should i lity of having trans be taken as with the transmitter (cells 13,

'.13a, etc.) in order that a current impulse does'not simultaneously influence another band indirectly.

, Numerous modifications of my. invention.

ivvill readil .occur to those skilled in the art.

- According y, it isintended that the application be limited only bythe scope of the recording said communications on records,

transmitting the communications on one record, employing the gaps in the sets 05 oscillations transmitted-from the first rec rd for 0nd record, and stopping the transmission of oscillations from the second record when the pause between oscillations in the. first record has terminatedand continuing thetransmiss'ion of oscillations from the first record.

2. A method of transmitting in succession a plurality of communications, comprising recording said communications on a plurality of bands, transmitting the oscillations transmitting setsof oscillations from a secfrom the first band, utilizing the pauses in the oscillations of the first band, for transmittin g the oscillations of a second hand, utilizing the concurrent pauses in the oscillations ofthe first and second bands for transmitting the oscillations ofthe third band, terminating the transmission. over the succeeding bands when the pauses in the preceding bands have terminated, and again transmittin the oscillations from the said preceding ban s. a

'3;.A method for transmitting a plurality of communications in succession,.comprising recording said communications on a plurality of bands, utilizing the pauses in the oscil'lations ofthe first band to transmit oscillations from a second hand, utilizin 'those pauses in the oscillations of the secon band which'are concurrent with the pauses in the first band to transmit. oscillations from a third band, terminating the transmission of bridged, continuin the transmission from the said preceding bands, and intermittently changing these uential relation of the bands as possible over the varir v 1 oscillations from the succeeding'bands when thefpauses 1n the preceding bands are to each otherw ereby the transmission time 

